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Descriptions

Sea tide heights predicted one year
in advance are manipulated to give accelerations
in centimeters per second per kilometer for the
distances San Francisco to Humboldt Bay and
Humboldt Bay to Astoria. Comparison of these
accelerations to various earth-moon-sun lineups
shows the accelerations are controlled by the
29.53 day lunar synodic cycle. The lunar
tropical (27.32 day) and the anomalistic
(27.5 day) cycles modify the tide's semidiurnalness
and range. Owing to their different periods,
these cycles come into and out of phase through
time. The declination of the sun due to the
tilt of the earth's axis imparts changes from
solstice to equinox and equinox to solstice.
Comparison of the summers of 1972-1975 shows
that some earth-moon-sun lineups do not recur
each summer. Some lineups do recur each summer
but at a different time of the summer. The
periodicities of the earth-moon-sun alignments
give an ever changing nature to the level of
the sea. Atmospheric phenomena may be strongly
influenced by the sea level at one time and
only weakly influenced at another time. Thus,
it is necessary to understand the sea level
changes driven by the earth-moon-sun alignments
to predict atmospheric conditions.